File format

The format is "property=value". value is an integer. You may specify only one option per line. Comments may be added by starting a line with the '#' character.

Here is an example file

# Set stdv mode to PAL (as used in Europe)
sdtv_mode=2
# Force the monitor to HDMI mode so that sound will be sent over HDMI cable
hdmi_drive=2
# Set monitor mode to DMT
hdmi_group=2
# Set monitor resolution to 1024x768 XGA 60Hz (HDMI_DMT_XGA_60)
hdmi_mode=16
# Make display smaller to stop text spilling off the screen
overscan_left=20
overscan_right=12
overscan_top=10
overscan_bottom=10

And here is another example file, containing extended documentation of features: link.

Video mode configuration

Video mode options

sdtv_mode defines the TV standard for composite output (default=0)

sdtv_mode=0 Normal NTSC
sdtv_mode=1 Japanese version of NTSC – no pedestal
sdtv_mode=2 Normal PAL
sdtv_mode=3 Brazilian version of PAL – 525/60 rather than 625/50, different subcarrier

sdtv_aspect defines the aspect ratio for composite output (default=1)

sdtv_aspect=1 4:3
sdtv_aspect=2 14:9
sdtv_aspect=3 16:9

sdtv_disable_colourburst disables colour burst on composite output. The picture will be monochrome, but possibly sharper

sdtv_disable_colourburst=1 colour burst is disabled

hdmi_safe Use "safe mode" settings to try to boot with maximum hdmi compatibility.

framebuffer_depth console framebuffer depth in bits per pixel. Default is 16. 8bit is valid, but default RGB palette makes an unreadable screen. 24bit looks better but has corruption issues as of 20120615. 32bit has no corruption issues but needs framebuffer_ignore_alpha=1 and shows the wrong colors as of 20120615.

framebuffer_ignore_alpha set to 1 to disable alpha channel. Helps with 32bit.

config_hdmi_boost configure the signal strength of the HDMI interface. Default is 0. Try 4 if you have interference issues with hdmi. 7 is the maximum.

Which values are valid for my monitor?

Your HDMI monitor may support only a limited set of formats. To find out which formats are supported, use the following method.

Set the output format to VGA 60Hz (hdmi_group=1 hdmi_mode=1) and boot up the Raspberry Pi

Enter the following command to give a list of CEA supported modes

/opt/vc/bin/tvservice -m CEA

Enter the following command to give a list of DMT supported modes

/opt/vc/bin/tvservice -m DMT

Enter the following command to show your current state

/opt/vc/bin/tvservice -s

Enter the following commands to dump more detailed information from your monitor

/opt/vc/bin/tvservice -d edid.dat/opt/vc/bin/edidparser edid.dat

The edid.dat should also be provided when troubleshooting problems with the default HDMI mode

Boot options

disable_commandline_tags Stops start.elf from filling in ATAGS (memory from 0x100) before launching kernel

cmdline (string) Command line parameters. Can be used instead of cmdline.txt file

kernel (string) Alternative name to use when loading kernel.

kernel_address address to load kernel.img file at

ramfsfile (string) ramfs file to load

ramfsaddr address to load ramfs file at

initramfs (string address) ramfs file and adress to load it at (it's like ramfsfile+ramfsaddr in one option). NOTE: this option uses different syntax than all other options - you should not use "=" character here. Example:

GPU core, h264, v3d and isp should all be integer divisors of pll_freq.
So core_freq=480 sets pll_freq=960. That would allow a v3d_freq/h264_freq/v3d_freq of 320 with an integer divider of 3.

This is not necessary with "avoid_pwm_pll=1".

Tested values

The following table shows some successfull attempts of overclocking. These settings may not work on every device and can shorten the life of the Broadcom SoC. Warranty will be voided if overvoltage is used.

arm_freq

gpu_freq

core_freq

h264_freq

isp_freq

v3d_freq

sdram_freq

over_voltage

over_voltage_sdram

750

255

450

900

250

500

900

275

500

900

450

450

930

350

500

1000

500

450

6

1000

500

500

6

References

↑ 1.01.11.21.3What this means is that you can specify -16 and expect about 0.8V as the GPU/core voltage. This is 0.4V below the normal value of 1.2. If you specify 16, you'd get 0.4V ABOVE the normal value of 1.2V, or 1.6V. The fact that someone carefully specified "8" and "1.4V" as the upper limit in the examples leads me to think that it is likely to shorten the life of your raspberry pi significantly if you would specify values above "8". So: don't specify values above zero, but if you do, don't go above 8.